void DecryptBufferLRW128 (byte *buffer, uint64 length, uint64 blockIndex, PCRYPTO_INFO cryptoInfo)
{
/* Deprecated/legacy */
int cipher = EAGetFirstCipher (cryptoInfo->ea);
int cipherCount = EAGetCipherCount (cryptoInfo->ea);
unsigned __int8 *p = buffer;
unsigned __int8 *ks = cryptoInfo->ks;
unsigned __int8 i[8];
unsigned __int8 t[16];
unsigned __int64 b;
*(unsigned __int64 *)i = BE64(blockIndex);
if (length % 16)
GST_THROW_FATAL_EXCEPTION;
// Note that the maximum supported volume size is 8589934592 GB (i.e., 2^63 bytes).
for (b = 0; b < length >> 4; b++)
{
Gf128MulBy64Tab (i, t, &cryptoInfo->gf_ctx);
Xor128 ((unsigned __int64 *)p, (unsigned __int64 *)t);
if (cipherCount > 1)
{
// Cipher cascade
ks = cryptoInfo->ks + EAGetKeyScheduleSize (cryptoInfo->ea);
for (cipher = EAGetLastCipher (cryptoInfo->ea);
cipher != 0;
cipher = EAGetPreviousCipher (cryptoInfo->ea, cipher))
{
ks -= CipherGetKeyScheduleSize (cipher);
DecipherBlock (cipher, p, ks);
}
}
else
{
DecipherBlock (cipher, p, ks);
}
Xor128 ((unsigned __int64 *)p, (unsigned __int64 *)t);
p += 16;
if (i[7] != 0xff)
i[7]++;
else
*(unsigned __int64 *)i = BE64 ( BE64(*(unsigned __int64 *)i) + 1 );
}
FAST_ERASE64 (t, sizeof(t));
}
void EncryptionModeLRW::EncryptBuffer (byte *data, uint64 length, uint64 blockIndex) const
{
size_t blockSize = Ciphers.front()->GetBlockSize();
if (blockSize != 8 && blockSize != 16)
throw ParameterIncorrect (SRC_POS);
byte i[8];
*(uint64 *)i = Endian::Big (blockIndex);
byte t[Cipher::MaxBlockSize];
for (unsigned int b = 0; b < length / blockSize; b++)
{
if (blockSize == 8)
{
Gf64MulTab (i, t, (GfCtx *) (GfContext.Ptr()));
Xor64 ((uint64 *)data, (uint64 *)t);
}
else
{
Gf128MulBy64Tab (i, t, (GfCtx *) (GfContext.Ptr()));
Xor128 ((uint64 *)data, (uint64 *)t);
}
for (CipherList::const_iterator iCipherList = Ciphers.begin();
iCipherList != Ciphers.end();
++iCipherList)
{
const Cipher &c = **iCipherList;
if (c.GetBlockSize () != blockSize)
throw ParameterIncorrect (SRC_POS);
c.EncryptBlock (data);
}
if (blockSize == 8)
Xor64 ((uint64 *)data, (uint64 *)t);
else
Xor128 ((uint64 *)data, (uint64 *)t);
data += blockSize;
IncrementBlockIndex (i);
}
Memory::Erase (t, sizeof (t));
}
